Your body is trying to get rid of toxins. The skin is one of the 4 excretory organs of the body including also lungs, kidney and liver. The colon is not an excretory organ since it is outside the body proper. The site below tells you the best foods to eat for health and why, with many sources not just one opinion. Also it uses common sense which is not so common in our society.
Pollution is so bad and getting worse everyday so you should avoid fish especially the fish that eat a lot of fish like shark, swordfish and tuna. The above diet can keep your body cleaner.Healthy Diet>
Also here is an article on using your animal instinct to eat the healthiest food.Eating Healthy